Use Zar stain, it is much easier to work with than Minwax and gives a much better finish. You really don't need a wood conditioner on oak, it is more often used on pine to give a more even finish. I did my floors years ago and used Zar stain, wiped the floors down later with paint thinner to even the finish, and then used a polyurethane over the finish. I recommend that you use at least two coats of polyurethane over one coat of stain. Lightly sand between coats. You might consider using flexible sanding sponges from 3M because of the shape of the railing. You could use up to three coats of poly on the handrail. Do not use a Spar Urethane, it is made to be flexible for exterior use and tends to be a softer finish.

Ditto on the Zar stain!!!

The stuff is pretty thick, and therefore goes literally FIVE times farther than Minwax, which like applying Coffee!
* Nothing "wrong" with that, except it's harder to control such thin stains.
* It's pretty easy to "woodgrain" with Zar on metal doors, etc., because it's so heavy-bodied.

>>> Normally...ONE coat of stain, unless it's just not getting dark enough.
>>> Poly-coats...IMO...3 or 4 on handrails. TWO coats barely starts to look even. Coats 3 & 4 will make a project look MUCH smoother!!
>>> Use the best brush for Oil paints you can afford - for doin' the Oil-Polyurethane coats.
>>> Floors??? You don't wanna hear this, but if you can do 4 or 5, you'll have a great initial "wear-layer" that won't look worn nearly as fast. Furniture is "verbotten" for a WEEK though!

Zar's Antique-Flat Oil-Poly, & the Satin Oil are the most popular here.

Faron

I agree with faron79, Zar is the best stain available on the market. Minwax pales in comparison. I personally like a high gloss finish. I used McCloskey's Gym Seal on my hardwood floors 13 years ago and it still looks good. At the time, I did not have access to the Zar Polys. Getting ready to do three bedrooms in Zar Cherry Stain and topcoat with high gloss poly.

There is no real reason to sand after staining. Since there is no finish on the wood to protect the stain layer, you could end up sanding some of the stain off. Just sand between coats of poly.